Extension-ladder.



A. A. BARNES. EXTENSION LADDER.

APPLICATION FILED JUNE 1, 1910. RENEWED MAR. 21, 1911.

Patented June 13,1911.

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ALFRED A. BARNES, OF HILLYARD, WASHINGTON, ASSIGNOR OF ONE-HALF TO ALBERT L. PIERCE, 01? HILLYARD, WASHINGTON.

EXTENSION-LADDER.

Application filed June 1, 1910, Serial No. 564,421.

To all whom it may concern:

Be it known that I, ALFRED A. BARNES, a citizen of the United States, residing at Hillyard, in the county of Spokane and State of l/Vashington, have invented certain new and useful Improvements in ExtensionLadders, of which the following is a specification.

This invention relates to improvements in extension ladders which are provided with locks for holding the ladder sections at adjustment, and it consists in a novel construction and arrangement of parts to be hereinafter described and claimed.

. It is the object of the invention to provide a lock of the kind stated which is simple in structure, and also one which is automatic in operation, and which will securely hold the sections at adjustment.

In the accompanying drawing Figure 1 is a front elevation of an extension ladder showing the application of the invention, and Fig. 2 is an enlarged transverse section thereof.

The two ladder sections are indicated at 5 and 6, respectively, the former being the lower section, and the latter the upper section, or the one to be extended. At the top of the section 5 are clips 7 for holding the two sections together, and one of the rungs 8 of the section 5 carries a pulley 9 over which passes a line 10 which is made fast to one of the rungs 11 of the section 6, whereby the latter may be raised or lowered. To the inner faces of the side members or standards of the section 6 are pivotally mounted at 12, pendent latches 13, which are spread at their lower ends, so that said end, on one side, extends into the plane of the rungs 8. The lower edges of the latches are also made concave, so that a better hold on the rungs 8 may be had. In the side members or standards of the section 6, below the pawls 13, is journaled a rock shaft 14 extending parallel to the rungs of the two sections. From this shaft projects outwardly sufficiently so that it may strike the rungs 8, an arm 15. The shaft is also connected to the latches 13 by arms 16 formed integral with, or rigidly secured to the shaft. The connection is a loose one, to permit a certain amount of lost motion, the latches having slots 17, and the arms having at their outer ends a lateral bend 18 into the slots.

In use, the section 6 is elevated by means Specification of Letters Patent.

Patented June 13, 1911. Renewed March 21, 1911. Serial No. 615,959.

of the line 10. During the upward movement of the section the free ends of the latches strike the rungs 8, and are thereby swung outwardly to clear said rungs. The connection between the latches and the shaft 1 1 being a loose one, this swinging movement of the latches may take place without interference from the shaft and the connection. hen the arm 15 strikes the rungs 8, the shaft 14 is rocked, and through the arms 16, the latches are swung inwardly in the direction of said rungs. The distance between the latches and the arm 15 is such that the lastmentioned swing of the latches takes place when they are opposite the space between the rungs 8. It will therefore be evident that when the section 6 reaches the desired elevation, and is then dropped slightly, the latches will engage the next rung below, whereupon said section is locked. The latches are swung far enough inwardly to seat squarely on the rung, and by the concave edge of the latches, a firm hold is obtained.

To lower the section 6, it is elevated until the latches strike the rung 8 next above the one on which the latches seated, whereupon they swing outwardly from said rung and clear the same. The latches are thus restored to their normal pendent position, and at the same time, the arms 16 and the arm 15 are restored to their normal position. The section 6 is now lowered, and every time the arm 15 strikes one of the rungs 8, it swings upwardly and rocks the shaft in a direction to swing the arms 16 outwardly from the rungs 8, thereby swinging the latches also outwardly from said rungs to clear the same. This swinging movement takes place automatically as each rung is passed, thus enabling the section 6 to be quickly and easily lowered.

The device herein described is very simple in structure, and has no complicated parts to get out of order. It is reliable in opera tion, and can be readily applied to any ordinary extension ladder, without modifying or altering the structure thereof, and it effectually serves the purpose for which it is designed.

I claim:

The combination with an extension ladder, of a transversely slotted and pivoted. latch carried by one of the ladder sections, said latch normally having its free end extendmentioned arm being such that said arm 10 tl L f tl f tl tl mg m 19 p me 0 1e rungs 0 1e 0 ler strikes the rungs when the latch is opposite section, and engageable thereby, a rock shaft I carried by the first-mentioned section below i the space therebetween.

the latch, an arm projecting from the rock In testimony whereof I affix my signature shaft into the plane of the rungs of the other in presence of tWo Witnesses. A

section, and engageable thereby, and another ALFRED A. BARNES. arm carried by the rock shaft, and extending loosely into the slot of the latch, the distance between the latch and the first \Vitnesses H. E. SMITH, DAVID EMERSON.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

